Project Summary/Abstract Critical gaps in our understanding of surgical site infections (SSI), the second most commonly reported healthcare-associated infection in adults and children, prevent us from accurately identifying at-risk patients and focusing preventive actions. Children and ambulatory surgical patients represent two overlapping groups for whom basic knowledge of SSI incidence and risk factors is lacking. Little is known about the epidemiology of SSI after the most commonly performed pediatric surgeries. Similarly, few data support the prevailing assumption that ambulatory surgeries are associated with a low risk of SSI. Because outpatient surgery accounts for more than 75% of all surgical procedures conducted in the United States, the burden of these infections could be quite large even if the SSI rate is relatively low. Given finite infection prevention and control resources, new strategies to conduct efficient and targeted SSI surveillance are badly needed. The electronic health record (EHR) holds promise as a tool to increase our capacity to accurately and efficiently track patient outcomes after health encounters across varied settings, particularly when the number of patients under observation is large. The potential advantages of EHR-facilitated surveillance of SSIs are particularly evident for ambulatory surgical patients, for which there are large numbers of exposed patients, each of whom may have a relatively low risk of experiencing an adverse outcome. Our proposal examines key issues requested in the SEN, by 1) characterizing the epidemiological aspects SSI, 2) focusing on ambulatory surgery, and 3) using an EHR to guide surveillance across various settings of care. Aim 1 will define the incidence of and risk factors for SSI after ambulatory pediatric surgery using a prospective cohort study of patients across a large pediatric healthcare network and rigorous, comprehensive SSI surveillance techniques to establish a gold standard. Aim 2 will determine the EHR data elements associated with SSI and evaluate the performance of an EHRbased surveillance algorithm for identifying SSI as compared to the gold standard surveillance. Finally, Aim 3 will yield a vendor-agnostic, EHR-embedded SSI surveillance workstation that will be validated during the final year of funding. Upon completion of the project, a detailed technical appendix specifying the implementation process for the SSI surveillance workstation will be provided and any modifications to the framework will be provided open source and free of charge.